In an interview with the film's director Kenji Nagasaki with Newtype Magazine (as shared by @aitaikimochi on Twitter), Nagasaki explained the reasoning behind the decision to set the film three full arcs after the current Shie Hassaikai/Internship arc running in Season 4.

As Nagasaki broke it down, the characters have evolved toward a point where they could mine a great new story, "Deku and Bakugo are both remarkable characters, but they have different relations towards each other. However, their interaction with each other changes over time and as they both grow stronger, it was quite easy for us to create a story involving that."

Even going as far as to tease that some of the film's events "will only happen" in the film itself, it seems like it's going to be tough for some fans to watch the new film. While there certainly will be a draw, there also might be many events unwittingly spoiled for fans who have yet to read through the manga themselves. Especially when it comes to the importance of new pro heroes like Hawks, who is being teased as playing a critical role in the film.

My Hero Academia: Heroes Rising is currently slated for a release in Japan on December 20th, but unfortunately there is no confirmation of an English language release as of this writing. The film is currently described as such, “A must-see story full of passion!! In this movie, Deku, Bakugo, Ochaco, Todoroki, and all the other members of Class A will make an appearance! Even though All Might was admired by [many] all around the world, it was with a sad heart that he had to give up his hero role as the Symbol of Peace. Because of this, a dark force who was moving behind the scenes, a villain named Nine who can be considered the greatest villain thus far.”

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